Automatic control system for reactors



Aug. 16, 1949. E. T. ARTERS 2,479,289

AUTOMATIC CONTROL SYSTEM FOR REACTORS Filed June 9, 1945 Load /8 1o WITNESSESI 44- 4o 45 6/ 63 64 62 4e .52 47 INVENTOR Patented Aug. 16, 1949 AUTOMATIC CONTROL SYSTEM FOR REACTORS Edward T. Arters, Pittsburgh, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application June 9, 1945, Serial No. 598,473

6 Claims.

My invention relates, generally, to control systems and has reference, in particular, to automatic switching systems for controlling the reactive energy in power systems.

Generally stated, it is an object of my invention to provide a control system that is simple and inexpensive to manufacture and is easy to operate.

A more specific object of my invention is to provide for controlling the reactive energy of an electric circuit by selectively connecting to the circuit two reactors, one of which has twice the reactance of the other, so as to provide three equal steps of reactance.

It is also an object of my invention to provide for obtaining the greatest number of equal steps of reactance with the least amount of equipment.

Another object of my invention is to provide for using a single, sensitive, control relay, responsive to the reactive energy of a power circuit, for controlling the connection of a plurality of reactors to the circuit.

Yet another object of my invention is to provide for using a sequence relay for selectively effecting the connection of a pair of reactors to a power circuit under the control of a single control relay responsive to the reactive energy of the circuit.

Other objects will in part be obvious, and will in part be explained hereinafter.

In accordance with one embodiment of my invention, two shunt reactors, one having double the reactance of the other, are used to provide three equal steps of reactance for compensating for the effects of the charging current of a transmission line. A single control relay responsive to the reactive energy of the line controls the connections of both reactors to the line. A sequence relay normally provides for effecting connection of the smaller reactor to the line under the control of the control relay to provide the first step of reactance. Upon the connection of the smaller reactor, the sequence relay operates to provide for connecting the larger reactor to the line under the control of the same control relay to provide the second step of reactance. When the larger reactor is connected, the smaller one is disconnected, and is thereupon again placed under the control of the same control relay for reconnection to the line to provide the third step of reactance.

For a more complete understanding of the nature and scope of my invention, reference may be made to the followin detailed description, which may be studied in connection with the accompanying drawing in which the single figure is a diagrammatic view of an automatic switch ing system embodying the invention in one of its forms.

Referring to the single figure of the drawing, the reference numeral I may denote, generally, an automatic switching system comprising circuit breakers II and I2 for controlling the conmotion of reactance devices such as the banks of shunt reactors l4 and I5, respectively, to the conductors ll of an electric circuit or a transmission line which connects a load I8 to a suitable power source, for the purpose of neutralizing the effect of the charging current of the line. In order to provide three equal steps of reactance, the reactors I5 preferably have twice the reactance of the reactors Hi.

The circuit breakers I I and I2 may be of any suitable type being, for example, provided with operating windings 20 and 2| disposed to be energized by closing switches 22 and 23, having operating windings 24 and 25, respectively. Cutoff relays 26 and 21, having operating windings 28 and 29, respectively, may be provided for effecting deenergization of the operating windings of the closin relays when their respective circuit breakers close. Each of the circuit breakers may be provided with trip means comprising, for example, trip windings 30 and 3| for effecting disengagement of latch members 32 and 33, respectively. The circuit breakers may be provided with control switches 34 and 35, respectively, for connecting them for either manual Or automatic control. The control switches 34 and 35 may be of any suitable type comprising, for example, switches of the drum type, which may be manually rotatable for effecting energization of either the closing switches or the trip windings, and operable to a third position by moving the handle axially to connect the circuit breakers for automatic control.

In order to provide for controlling the circuit breakers II and I2 automatically, auxiliary trip relays 36 and 31 may be provided having operating windings 38 and 33, respectively. These auxiliary trip relays function to provide for energizing the trip windings 30 and 3| when the control switches 34 and 35 are in the automatic position.

In order to provide for selectively connecting the banks of reactors I 4 and I5 to the conductors I! in accordance with a condition effected by the reactive energy of the circuit, only a single sensitive control relay 40 responsive to the reactive energy of the circuit is utilized. The relay 4!] may be provided with a movable armature II for selectively engaging contact members 40a and 4%, depending on whether the reactive energy of the circuit is leading or lagging and exceeds predetermined values thereof.

In order to prevent pumping of the control system due to momentary fluctuations in the reactive energy of the circuit, time delay means 42 and 43 may be provided for efiecting operation of the circuit breakers II and I2 under the control of the control relay 40 only after the reactive completing operating circuits for the closingre- V lays and trip means of the circuit breakers. The bimetallic elements-48 and ,49 of the time delay means 42 may be mechanically, connected in opposed relationrso as to neutralize the effectsof variations in ambient temperature. The bimetallic elements 5|. and, 52 of the time delay means 43 may be similarlyconnected;

In order toprovidefor. effectingselective con-. nection and disconnection of the banks of reactors l4 and |5to and from the..circuit, a see quence relay 54 may be utilized. This sequence relay may be disposed-to normallyconnect the time delay means 42 foreffecting connection of the bank of reactors l4 to the circuit under the control of therelay40. An operating winding 55 may be provided for operating the relay whenever the time delay means 43 operates to effect connection of the bank of reactors l5 to the circuit while the circuit breaker His closed; Reset means comprising a reset winding 55 may be provided for retracting an armature 51 from engagement with a latch member 58=to return the sequence relay 54 to its normalposition whenever the time delay means 43 operates to open the circuit breaker l2. 7 a

In order to provide threeequal steps of reactance provision may be made .for tripping the cir-' cuit breaker'll whenever the circuitbreaker I2 is closed in response'to a continued demand for more inductive reactance after thereactors l4 are connected to the circuit. An additional time delay means 60 may be provided for controlling the connection of the reactors M to the circuit after the circuit breaker 12" connects the reactors |5 thereto. The time delay means 60 may be of any suitable type comprising, for example, transformers 6! and 52 having primary windings disposed to be selectively energized under the control of the control relay 40 and having bimetallic elements 63 and 64 connected to the secondary winding thereof for effecting energization of the operating winding 65 of an auxiliary closing relay 66 which energizes the closing relay 22, and an auxiliary tripping relay 61 provided with an operating winding 68 for energizing the trip winding 30.

When the system is in the deenergized position, as shown, the control relay 4|] will close its contact members 400. and 4012 depending on whether the reactive energy of the circuit is leading or lagging, and in excess of a predetermined amount. With the control switches 34 and 35 operated to the automatic position, an energizing circuit is provided for the primary winding of the transformer 44 of the time delay means 42, extending from the right-hand conductor through conductors l0 and II, armature 4|, contact member 40a, conductor 12, contact member 340, conductor 13, back contact member 5402 of the sequence relay 54, back contact member I22 of the circuit breaker l2, conductor '55, primary winding of the transformer 44, conductors l6, l8 and 19, back to the intermediate conductor ll. After a predetermined time the bimetallic element 48 deflects and engages contact member 42a, to provide an energizing circuit for the operating winding 24 of the closing switch 22 through back contact member 2627 of the cut-off relay 26 to the intermediate conductor H. The closing switch 22 is thus operated and provides an energizing circuit for the operating winding of the circuit breaker through contact members 22a. ircuit breaker operates and connects the bank of reactors l4 to the conductors H for the first step of reactance.

When the inductive reactance or the circuit increases above the predetermined value for which the control relay 4G closed its contact members 4%, contact members 46a open, and the system operates with the reactors I4 connected to the conductors ll. Should the load conditions change so that the inductive reactance of the circuit increases still further to the predetermined value for which contact members 48b close, an energizing circuit is provided for the primary winding of the transformer 45 of the time delay means 42 from armature 4| through contact member 40b, conductor 50, contact member 34d,

conductor 53, contact members I27, conductor 69, primary winding of transformer 45, conductors 15, 18 and E8, to the intermediate conductor After a predetermined time the bimetallic element 49 engages contact member 421) and provides an energizing circuit for the operating winding 38 of the auxiliary trip relay 36. The relay 36 operates and provides an energizing circuit for the trip winding of circuit breaker through contact members 36a so that the latch member 32 is disengaged, opening this circuit breaker and disconnecting the reactors I4 from the conductors 11.

If, with the circuit breaker closed and the bank of reactors l4 connected to the conductors H, the inductive reactance of the circuit either remains at or decreases to a value for which the control relay 4i] closes its contact members Add, an energizing circuit is now provided for the primary winding of the transformer 46 of the time delay means 43. This circuit may be traced from the right-hand conductor |l| through conductors l0 and H, armature 4!, contact member 46a, conductors i2 and 39, back contact members My of the circuit breaker contact member 356 of the control switch 35, conductor 8| and 82, through primary winding of the transformer 46, conductors l8 and T9 to the intermediate conductor H. The bimetallic element 5| operates after a predetermined time engaging contact member 43a. An obvious energizing circuit is thereby established for the operating winding 55 of the sequence relay 54 through contact members 549, which thereupon operates to the latched position,

Operation of the sequence relay 54 provides an energizing circuit for the operating winding 25 of the closing switch 23 for the circuit breaker l2 extending from the intermediate conductor l1 through conductor 19, back contact members 2112' of the cut-off relay 2?, operating winding 25, conductors and 85, front contact member 540 of the sequence relay 54, conductors BI and 82, contact member 356, conductor 92, contact members lg, conductor 12, contact member 413a, armature 4| and thence back to the right-hand conductor ll. provides an energizing circuit for the operating The closing switch 23 operates and d winding 2| of the circuit breaker 12 through contact members 23a.

The circuit breaker l2 thereupon closes, connecting the bank of reactors l5 to the conductors I1. Closure of the circuit breaker l2 provides an energizing circuit for the trip winding 30 of the circuit breaker I extending from the right-hand conductor I! through conductors I and 88, front contact members |2e of the circuit breaker l2, front contact members 54a of the sequence relay 54, operating winding at, front contact members He of the circuit breaker ll, conductors 89 and 19 to the intermediate conductor l1. Circuit breaker thereupon opens, disconnecting the bank of reactors M from the conductors I! to complete the operation for connecting the second step of reactance to the circuit.

With the reactors |'5 connected to the conductors if the reactive energy of the circuit changes to the predetermined lagging value for which the control relay 40 operates to connect the armature 4| to contact member 4017, an energizing circuit is provided for the primary winding of the transformer 47 of the time delay means 43. After a predetermined time, the bimetallic element 52 engages contact member 43b to provide an energizing circuit for the operating winding 39 of the auxiliary trip relay 31. The trip winding 3| is thereby energized through contact members 31a to effect disengagement of the latch member 33, thus opening the circuit breaker l2 and disconnecting the reactors Hi from the conductors l1.

Should the disconnection of the reactors I result in the operation of the control relay 4!) to connect armature 4| and contact member la, the reactors It may be reconnected to the conductors I! in the manner as described hereinbefore, since the sequence relay 54 is returned to the original or normal position upon operation of the auxiliary trip relay 31 by energization of the reset winding 56. This energizing circuit extends from the intermediate conductor through conductor 19, operating winding 56,

front contact member 54b, front contact member 310 of the auxiliary trip relay 31, conductors 90 and to the right-hand conductor With the reactors l5 connected to the conductors if the reactive energy of the circuit reaches the predetermined leading value for which the control relay 4D is set, the relay will again operate so that armature 4| engages contact member 49a. Since the circuit breaker H is open, the sequence relay 54 is in its operated position and the circuit breaker I2 is closed, an energizing circuit is therefore provided for the primary winding of the transformer 6| of the time delay means 60.

This circuit extends from the right-hand conductor I! through conductors 10 and 1|, armature 4|, contact member 40a, conductors l2 and 9|, front contact members 54c, front contact members IZIc, conductor 92, contact member 3'5e, conductor 8|, contact member 34f, back contact members lh, primary winding of transformer 6|, conductors l6, l8 and 19 to the intermediate conductor l1. After a predetermined time the bimetallic element 64 operates to engage contact member 60a, thereby providing an energizing circuit for the operating winding 65 of auxiliary control relay 66.

The auxiliary control relay connects the operating winding 24 of the closing switch 22 of the circuit breaker H to the source through contact members 66a to provide for operation of the cir- 6 cuit breaker II to connect the reactors H to the conductors l1, thus providing a third equal step of reactance.

Should the reactive energy of the circuit subsequently increase suihciently, to reach the lagging value for which the armature 4| engages contact members 40b, the additional time delay means 60 operates under the control of the control relay 40 to close contact members 60b and effect energization of the operating winding 68 of the auxiliary trip relay 61. The trip winding 3|! is thereby energized to open the circuit breaker Upon a further increase in the reactive energy, the control relay 48 again operates so that armature 4| engages contact member 40b, whereby the primary winding of the transformer 41 of the time delay means 63 is energized for efiecting operation of the auxiliary trip relay 3! to effect operation of the circuit breaker l2 to disconnect the reactors I5. Since the reset winding 58 of the sequence relay 54 is energized through contact members 310 of the auxiliary trip relay 31, the sequence relay 54 is thereby restored to its normal operating position and the operation of the circuit breaker H is thereupon returned to the control of the reactive energy control relay 40.

From the above description and the accompanying drawing it will be apparent that I have provided, in a simple and effective manner, for selectively controlling the connection of a plurality of reactors to a load circuit under the control of a single selective control means. By using two reactors, one of which has twice the reactance of the other, and switching the reactors in a predetermined sequence, three equal steps of reactance may be provided in increasing or decreasing amounts. By using a sequence relay responsive to the operating condition of the circuit breakers for controlling the connections of the reactive energy control relay, a simple and eflective control system is provided utilizing a minimum of equipment. The maintenance and operation of the control system are thus greatly simplified.

Since certain changes may be made in the above-described construction and different embodiments of the invention may be made without departing from the spirit and scope thereof, it is intended that all the matter contained in the above description and shown in the accompanying drawing shall be considered as illustrative and not in a limiting sense.

I claim as my invention:

1. For use with an alternating-current power system, a first reactance device, a second reactance device having more reactance than the first device, first and second switch means for connecting the first and second reactance devices to the power system respectively, circuit means for opening the first switch means when the second switch means closes, control means responsive to an electrical condition of the power system which is affected by the reactivekilovoltamperes of the system for effecting closing of the first switch means, and sequencing means responsive to closure of the first switch means before the first switch means open to connect the second switch means for closure under the control of the control means and responsive to closing of the second switch means to reconnect the first switch means for closing under the control of the control means.

2. For use with a power system, a pair of reactance devices one being of double the value of the other, switch means individual to each of the reactance devices for connecting and disconnecting the devicesto and from the power system, control means responsive to the reactive energy of the system for operating the switch means to connect the reactance devices to and disconnect them from the power system, sequence means normally connecting the switch means of the smallerof the reactance devices for operation under the control of the control means responsive to closure of said switch means to connect the other switch means for operation under control of the control means before the switch means of the smaller of the reactance devices opens, and circuit means'responsive to closure of the other switch means for efiecting operation of the sequence means to return the switch means of the smaller of the reactances to the control of the control means. A

-. 3. A controlisystem comprising, a first reactance device, a second reactance device having twice'the amount of reactance as the first device, a first switch means for controlling the connection of the first reactance device to a power system, a secondswitch means for controlling the connection of the second reactance device to the power system, control means responsive to an electrical condition of the system affected by the reactive energy of the system for selectively effecting the opening and closing of the switch means, sequence means normally connecting the first switch means for operation under the control of the control means and operable'to connect the second switch means for operation under the control means as soon: as the first switch means closes, circuit means after the second switch means closes responsive to closure of the second switch means for openingthe first switch means, andmeans responsive to closure of the second switch means for connecting the control means to efiect operation thereof to the normal position whereby the first switch means is reconnected for operation under control of the control means.

' 4. A control system comprising, a first reactor, a second reactor having twice the reactance of the first, first and second switch means operable to connect the reactors to a power system, a control relay responsive-to the reactive energy of the syst'em, a sequence relay normally connecting the first switch means for operation under control of the control relay and operable upon closing of said first switch means to connect the second switch means for operation, means responsive to opera-' 5. A control system'comprising, a first reactor, a second reactor having twice the reactance of the first reactor, first and second switch means for respectively connecting the reactors to an electric circuit, control means responsive to the reactive energy of the means for operating the first and second switch means, circuit means normally connecting the first time delay means for operation at a predetermined time after a predetermined energy condition occurs in the circuit, circuit means responsive to closing of the first switch means to connect the sequence relay for operation to connect the second time delay means for operation under the control of the control means, circuit means responsive to: closing of the second switch means for opening the first switch means after the second switch means closes, an additional time delay means for efiecting operation of the first switch means, circuit means responsive to opening of the first switch means and closing of the second switch means for connecting the additional time delay relay for operation under the control of the control means.

6. In a control system, a first reactor, a second reactor havin twice the reactance of the first reactor, first and second switch means for respectively connecting the first and second reactors to an electric circuit, control means responsive to predetermined reactive energy conditions of the circuit, first and second time delay means operable to effect operation of'the first and second switch means respectively, sequence means normally operable to connect the first time delay means for energization by the control means and operable to connect the second time delay means in place of the first time delay means when the second switch means operates, means for deenergizing the first switch means after the second switch means closes, and means including additional time delay means controlled by the control means for reclosing the first switch means.

EDWARD T. ARTERS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

